Two-temperature refrigeration system



8- 1943- E. T. MORTON 2,446,946

TWO-TEMPERATURE REFRIGERATION SYSTEM Filed March 8, 1943 Patented Aug. 10, 1948 TWO-TEMPERATURE REFRIGERATION SYSTEM Evans '1. Morton, Indianapolis, Ind, assignor, by mesne assignments, to Admiral Corporation, Chicago, 11]., a corporation of Delaware Application March 8, 1943, Serial No. 478,342

12 Claims.

1 This invention relates to improvements in refrigeration system in which two or more compartments of a single refrigerating unit are to be maintained at different temperatures. Such refrigerators usually have two compartments, one maintained at freezing temperature and the other at a more moderate temperature of about 40 Fahrenheit.

The object of the invention is the simplification of the mechanism primarily by the elimination of the pressure reduction valve heretofore located in the evaporator conduit at a point between the higher temperature compartment and the freezing compartment. In accordance with my present invention, 1 bring about the less violent evaporation or boiling in the coils associated with the higher temperature compartment and the more violent evaporation or boiling in the coils associated with the low temperature compartment by very materially restricting the size of the evaporating conduit associated with the higher temperature compartment, and also by re stricting the size of the conduit leading the refrigerant from the condenser to the higher temperature compartment. By reason of the restriction of the capillary tube leading from the condenser to the entrance of the evaporator coil of the higher temperature compartment, the pressureof the refrigerant in the tube leading to the firstevaporator is maintained continuously above the vaporization pressure even though the temperature of this tube is comparatively high. The size of the evaporator tube for the higher temperature compartment is such that a material reduction in pressure takes place in this latter tube. notwithstanding the fact that the velocity of the refrigerant through this restricted tube prevents a pressure drop equivalent to that at the entrance side of the compressor. The evaporator tube or conduit associated with the low temper-ature compartment of the refrigerator is many times the internal diameter of that of the higher temperature compartment evaporator and therefore the pressure in the evaporator associated with the freezing compartment of the refrigerator drops to substantially that at the entrance side of the compressor.

My invention is illustrated in the accompanying drawings, in which:

Fig. 1 is an illustration of a refrigerator unit provided with two compartments suitably insulated fromone another, and

Fig. 2 is a diagrammatic illustration of the electrical and refrigerant circulating systems of my improved refrigeration system.

The refrigerating unit of Fig. 1 comprises an upper compartment 4 and a lower compartment 5, separated from one another by spaced plates of glass 6 or other insulating material. The compressor unit 8, the condenser 9 and the accumulator iii are preferably located in the lower part II of the refrigerator unit. The evaporator circulating system is illustrated in Fig. 1 by the dotted line l2. 4

Referring more particularly to Fig. 2. the condu-it I 4 which extends vertically from the discharge side of the condenser 9, and connects at IS with the entrance to the-upper evaporator II,

is preferably of very small internal diameter, for

example, .04 inches for a domestic type refrigerator. The size of this conduit H is such that the pressure ordinarily maintained in the condenser creates such a velocity of flow of liquid refrigerant through the capillary conduit N, that no evaporation whatever takes place in this conduit. The conduit l6, constituting the evaporator for the higher temperature compartment of the refrigerator unit, is provided with an internal diameter more than twice as great and having a cross-sectional area more than four times as great as the diameter and area. of the capillary conduit ll. Nevertheless, the size of the upper evaporator conduit I6 is suillciently small that the velocity of the refrigerant therein creates such a resistance to flow that only a limited amount of evaporation takes place. This coil must be mounted with a continuous slope toward the bottom so that there will be no pockets in which liquid refrigerant can accumulate and from which uncontrolled evaporation will take place.

The evaporator coil l8, located in the freezing chamber of the refrigerator, is of much larger diameter than that of the coil l6 and, consequently, the evaporation which takes place in the coil It depends not upon the resistance to flow of the refrigerant therein, but upon the degree of pressure reduction maintained at the accumuwhich serves to open and closethecompressor circuit in accordance with the temperature of the upper refrigerator compartment, all of the conduit sizes having been so selected that when the temperature of the upper compartment is regulated to about 40 Fahrenheit, the temperature of the freezing compartment will be maintained in the neighborhood of zero Fahrenheit. I have found that in a domestic refrigerator the refrigerant delivery conduit ll may have an internal diameter of .04 inch, the upper evaporator conduit I! may have an internal diameter of .095 inch and the lower evaporator conduit it may have an internal diameter of .312 inch. With these dimensions and a length of 17 to 19 feet for conduit I laid spirally to lift the refrigerant from the lower compartment of the refrigerator unit to the top of the upper refrigerator compartment, satisfactory temperature differences between the upper and lower refrigerator compartments will he maintained.

Although my invention is illustrated as applied to a refrigerator having two compartments, it may be applied to a refrigerator having any number of compartments in which the temperature is graduated from high to low from the top of the refrigerator towards the bottom, and in which the size of the internal diameter of the evaporator coils is graduated from small to large in accordance with the temperatures desired in the different compartments. It will be understood that the form of evaporator conduit need not be that of a cylindrical tube and that the restriction to flow need not be uniform throughout the entire length of the higher temperature evaporator or throughout the entire length of the conduit leading to the entrance of the higher temperature evaporator. A multiplicity of restrictions spaced throughout the length of the delivery conduit and a multiplicity of restrictions spaced throughout the length of the upper evaporator conduit may be substituted for the continuous restrictions illustrated in the accompanying drawing.

While I have shown and described a preferred embodiment of my invention, it will be readily understood by those skilled in the art that variations may be made in the construction disclosed without departing from the basic features of my invention. I therefore do not wish to be limited to the precise construction disclosed, but wish to include within the scope of my invention all such modifications and variations which will readily suggest themselves.

Having thus described my invention, what I claim as newand useful and desire to secure by Letters Patent of the United States is:

l. The combination with an insulated cabinet having a food storage chamber therein, of partition means dividing said chamber into compartments one underlying another, and refrigeratin apparatus for cooling said chamber; said refrigerating apparatus including a liquefying unit and a continuous length of tubing connected at its opposite ends to said unit; said tubing being formed to provide an-evaporator and a capillary expansion tube device arranged to discharge into saideva/porator; said evaporator being made up of sections of successively increasing having a food storage chamber therein, of a paltition dividing said chamber into compartments one underlying another, and refrigerating apparatus for cooling said chamber; said refrigerating apparatus including a refrigerant liquefying unit and a continuous length of evaporator tubing operatively connected to said unit and with an expansion device interposed between the inlet end of said tubing and the outlet end of said unit; said evaporator tubing being made up of sections of successively increasing internal crosssection and arranged one in heat exchange relation with each of said compartments; the bore of each said sections of evaporator tubing being of uniform cross-sectional area from the inlet end thereof to the outlet end thereof; and the evaporator tubing being so arranged that the section having the bore of smallest cross-sectional area cools the uppermost compartment while the section having the bore of largest cross-sectional area cools the lowermost compartment.

3. The combination with an insulated cabinet having a food storage chamber therein, and a refrigerating apparatus in heat exchange relation to said chamber for cooling the same to provide superposed zones of different temperatures; said refrigerating apparatus including a refrigerant liquefying unit and a continuous length of evaporator tubing operatively connected to said unit and with an expansion device interpoud between the inlet end of said tubing and the outlet end of said unit; said evaporator tubing being made up of sections of successively increasing internal cross-section from the uppermost region to the lowermost region of said chamber; the boreof each said sections of evaporator tubing being of uniform cross-sectional area from the inlet end thereof to the outlet end thereof; and the evaporator tubing being so arranged that the section having the boreof smallest cross-sectional area cools the uppermost region of said chamber while a section having a bore of larger cross-sectional area cools a lower region of said chamber.

4. A refrigerator of the type having an insulated cabinet forming a food storage chamber therein, a refrigerant liquefying unit an expansion device connected to the outlet of said liquefying device, and a continuous length of evaporator tubing interposed between said expansion device and the inlet of said liquefying unit and in heat exchange relation to said food storage chamber; characterized by the fact that zones of decreasing temperature are produced in said chamber downwardly from the top thereof by making said evaporator tubing of sections of successively increasing internal cross-sectional area from the upper region to the lower region of said chamber, the cross-sectional area of each being uniform throughout the length thereof.

5. A refrigerator comprising in combination means forming a food storage chamber, a partition dividing the chamber into compartments, and refrigerating means for cooling the compartments to different temperatures. said refrigerating means comprising a refrigerant condensing unit, an evaporator conduit arranged in heat exchange relationship with each of said compartments, said evaporator conduits being connected in series and having restricted passageways therethrough, the restrictions decreasing in the same order as the desired temperature of the compartments decrease, means connecting the outlet of the last of said evaporator conduits to the inlet of said condensing unit. and an expansion device interposed between the outlet of said condensing unit and the inlet of the first of said evaporator conduits.

6. A refrigerator comprising in combination means forming a food storage chamber, and refrigerating means for cooling the food storage chamber so as to produce zones of decreasing temperature in the chamber downwardly from the top thereof, said refrigerating means comprising a refrigerant condensing unit, a plurality of evaporator conduits arranged in heat exchange relationship with the food storage chamher, said evaporator conduits being connected in series and having restricted passageways therethrough, the restrictions decreasing in the same order as the desired temperatures of the different temperature regions in said chamber decrease, means connecting the outlet of the last of said evaporator conduits to the inlet of said condensing unit, and an expansion device interposed between the outlet of said condensing unit and the inlet of the first of said evaporator units.

7. In a refrigerator having two or more compartments to be cooled to different temperatures, a refrigeration system comprising a delivery conduit provided with a highly restricted passageway throughout its length for delivery of refrigerant to the top of the higher temperature compartment of the refrigerator, an evaporator conduit for the higher temperature compartment and its outlet connected to the inlet to the delivery conduit for creating circulation of refrigerant through said conduits.

8. In a refrigerator having two compartments to be cooled to different temperatures, a refrigeration system comprising a restricted delivery conduit for delivery of refrigerant to the upper part of the higher temperature compartment of the refrigerator, an evaporator conduit having its inlet connected to the outlet of the delivery conduit and having a restricted passageway therethrough of less restriction than that of the delivery conduit and being located in heat exchange relationship with the higher temperature compartment of the refrigerator, an evaporator conduit having a lower restriction than that of the conduit for the higher temperature compartment located in heat exchange relationship with the lower temperature compartment, the conduit for the higher temperature compartment being connected in series with the conduit for the lower temperature compartment, and a refrigerant liquefying unit having its inlet connected to the outlet from said series of evaporator conduits and its outlet connected to the inlet to the delivery conduit for creating circulation of refrigerant through said conduits.

9. In a refrigerator having two or more compartments to be cooled to different temperatures, a refrigeration system comprising a refrigerant liquefying unit, an evaporator conduit for the higher temperature compartment of the refrigerator having a restricted passageway therethrough, a delivery conduit having its inlet connected to the outlet of the liquefying unit and having its outlet connected to the inlet of the evaporator conduitfor delivery of refrigerant from the liquefying unit to the higher portion of the restricted evaporator conduit, the delivery conduit having a passageway therethrough of greater restriction than that of the evaporator conduit, an evaporator conduit for the lower temperature compartment of the refrigerator having much less restriction than the conduit for the higher temperature compartment and connected in series with said first mentioned evaporatorcondult at a low portion thereof, and the evaporator conduit for the lower temperature compartment having its outlet connected to the inlet of the liquefying unit.

10. In a refrigerator having two or more compartments to be cooled to different temperatures, arefrigeration system comprising an evaporator conduit for the low temperature compartment having a restricted passageway therethrough and having a continuous slope from top to bottom, a delivery conduit having its outlet connected to the inlet of said evaporator conduit at the top thereof, the delivery conduit having a passageway therethrough of greater restriction than that of the evaporator conduit, an evaporator conduit for the lower temperature compartment having much less restriction than the conduit for the higher teunperature compartment and connected to the bottom of said last mentioned conduit so that said conduits are connected in series, and a refrigerant liquefying unit having its inlet connected to the outlet of said lower temperature compartment conduit and its outlet connected to the inlet of said delivery conduit for creating circulation of refrigerant through said conduits.

11. In a refrigerator having two or more compartments to be cooled to difl'erent temperatures, a refrigeration system comprising a delivery conduit having a highly restricted passageway therethrough for delivery of refrigerant to the top of the highest temperature compartment, evaporator conduits for cooling each compartment, said evaporator conduits being connected in series and having restricted passageways therethrough, the restrictions decreasing in the same order as the desired temperatures of the compartments to be cooled, the inlet of said series of evaporator conduits being connected to the outlet of the delivery conduit, and a refrigerant liquefying unit having its inlet connected to the outlet of said series of evaporator conduits and its outlet connected to the delivery conduit for creating circulation of refrigerant through said conduits.

12. In a refrigerator having two compartments to be cooled to different temperatures, a refrigeration system comprising a capillary delivery conduit for delivery of refrigerant to the upper part of the higher temperature compartment, an evaporator conduit having passageway therethrough of cross-sectional area approximately four times the cross-sectional area of the delivery conduit passageway and located in heat exchange relationship with the higher temperature compartment, an evaporator conduit connected in series with the first evaporator conduit and having a passageway therethrough of cross-sectional area of approximately sixty times the cross-sectional area of the delivery conduit passageway and locatedin heat exchange relationship with the lower temperature com- Bmmcgg cum pertinent, theinlet tosaid series of evaporator conduits being connected tothe outlet of the i igigggg N m delivery conduit. and a.- refrigerant liquefying unit having its inlet connected to the outlet from UNITED STATES PATENTS said series oi evaporator conduits and its outlet Numbe connected to the inlet to the delivery conduit for 1 622 ix m 1927 creating circulation oi. refrigerant through said 1 Blood 1941 conduits.

EVANS T. MORTON. I. 

